The router machine of the present invention may have many applications, and is particularly well adapted for making repetitive router cuts at predetermined positions in a workpiece. The router assembly of the router machine of the present invention may comprise one or two router devices. Where two router devices are provided, the blades of the router devices are opposed and coaxial. As a result, the router machine is capable of making simultaneous mirror image router cuts in both sides of a single workpiece, or in opposite sides of a stacked pair of workpieces. While not intended to be so limited, the router machine of the present invention is particularly well adapted to making simultaneous, mirror image router cuts in a stacked pair of stair stringers and, for purposes of an exemplary showing, will be described in this application of the machine. The router cuts made in the stair stringers are intended to accommodate treads and risers, if risers are present.
Router machines for making simultaneous, mirror image router cuts in stair stringers are, per se, known in the art. Such machines are normally provided with a router assembly having opposed router devices with coaxial, opposed router bits or blades. In the most frequently encountered prior art router machine of the type under discussion, the router assembly and its blades are guided by a rotatable stylus which runs inside an adjustable template. The stylus is positioned coaxially with the router blades or bits. The stylus is directed around the inside of the template by a pair of air cylinders. The air cylinders, in turn, are controlled by a series of valves mounted on the template. While such router machines operate well, they are very labor intensive to build, assemble and operate. The prior art router machines tend to be complex in structure, and considerable time and effort is required to modify the adjustable template when required, depending upon the type of stairway to be produced.
The router machine of the present invention is mechanically simple to build and operate. As will be set forth hereinafter, all pertinent information relating to the stairs is entered into the electronic control system by means of an operator interface. The electronic control system instructs two linear actuators to maneuver the router assembly along the desired paths of travel. When one router cut is made for one riser and/or tread, a material feed mechanism advances the stair stringers to the position for the next routing operation, the movement of the stringers being measured and monitored by an encoder wheel. When the prescribed number of router cuts has been made in the stringers, the router machine will automatically shut down.
Most prior art router machines of the type to which the present invention is directed use linear cross slides to support the router devices. The cross slides are difficult to keep clean and lubricated in a dirty environment. The router devices of the router machine of the present invention are supported on four sealed pillow block bearings. As a result, lubrication and dirt do not constitute a problem.